Hey guys, I have been working toward getting some real numbers pertaining to a propeller comparison for a while now. I have flown a Kiev prop on my HIghlander for a little over 400 hours in the past 14 months and I have gotten to be quite familiar with it's performance. It is undeniably a great prop, but those words alone don't really say much so I did a pull test with a digital scale and then flew with a clipboard on my lap for a while to write down some real world numbers. I don't claim to be a professional as this but at least it's a start. I was presented with the opportunity to test a Whirlwind prop and I tried to get a good baseline for comparison by setting the pitch for the same static RPM that my Kiev was set for. Alright, let's see if I can arrange these numbers in a way that makes sense.

I changed the pitch a little to achieve a static RPM of 5300. With all the other variables being the same except the temp had risen to 8C.

RPM IAS 4800 87 5000 90 5100 94 5200 96 5300 99 5400 102 5500 104

Oh, I forgot to mention - I had a spinner on the Kiev prop but I don't have one to fit the Whirlwind so it was done without one. After the pull test, I thought the Whirlwind (although it's a beautiful prop) was not gonna be worth much compared to the Kiev. I was wrong. Even though the numbers on the pull scale declared it to be a lesser performer, I taxied out to the runway and gave it a try. My Highlander leapt off the ground and climbed very impressively. I'm sorry that I can't give you any solid climb rate numbers because I don't have a VSI, but I have to say I was pleasantly surprised. Jak saw it too. Now he's drooling over my new Whirlwind prop, Haha! (He may wind up with it, he's quite the horse trader.) I also have to say that I was impressed with the increase in cruise speed. Now I'm interested in trying it again with a static RPM of about 5200. If I do I'll let you know.

I don't know enough about this to say how much the different temperatures affected the performance numbers, but if I'm not mistaken, our friend Jack Leroux might enlighten us on this subject.

I will try to post a picture or two of these props if anyone is interested.

No, I don't think I want to try a static setting of 5600. At that setting it is SO easy to over-rev your engine on take off.I'm not comfortable with that. Even when the static setting is 5400 the RPM's will climb VERY quickly when I level offso I have to keep the nose high and my hand on the throttle.

I am no expert on the subject of propeller propulsion either but I do try to understand it and try to learn all I can about it. Normally I wouldn't pay attention to someones posted IAS figures because they only mean something on your aircraft because our systems are not calibrated and are not identical. When I trained with the Brass Town Boys their aircraft IAS was out by 10 MPH so on our first flight Vic and I established what speed his aircraft stalled at. From there we figured out what our approach speeds and other "V" speeds would be. Once we had those down the IAS numbers meant everything on that aircraft only.

Your tests mean everything because you used the same test bed and scale to make the comparison with two different propellers. On the first and last test the temperature and barometric pressure are so close to each other that the figures are probably as good as you can get. Clearly your results indicate that the Whirlwind is producing better AS results than the Kiev is. Throughout our discussions it appears as if our IAS speeds are close so once I try the Kiev I will let you know what I get. Thanks for the comparison, these tests take a lot of time but they mean a lot to those contemplating what propeller to buy.

My Kiev is in the US and I will be picking it up at Sun and Fun, I should of waited to buy yours at a discounted price:(

Your tests mean everything because you used the same test bed and scale to make the comparison with two different propellers.

Yep!

No, I don't think I want to try a static setting of 5600. At that setting it is SO easy to over-rev your engine on take off.I'm not comfortable with that. Even when the static setting is 5400 the RPM's will climb VERY quickly when I level offso I have to keep the nose high and my hand on the throttle.

That's how I set the static on my RV12, around 5300, it was optimized for cruise and I didn't throttle-jockey so much like with the Highlander. Definitely go with what is comfortable, sounds like you're setting it up for best overall performance.

My Highlander is set with static at 5600 (field elevation 6750'). It doesn't redline on take off, but at full throttle cruise, if I pitch forward I hit redline in seconds. It's optimized for climb and I'm used to controlling over-rev with the throttle. With the altitude and heat, I need the extra HP from those extra revs.

Thanks again for the objective tests, I ordered a Prince Prop based on John Levy's recent post and will provide some data after I install it.

Yes, it does take a lot of time to gather this information. I had to loosen all the bolts, adjust the pitch, and re-torque everything 5 times before I finally got the static RPM's right where I wanted them but like you said - this information is really worthwhile. I am hoping that others will try to gather such information about other props and share with us. They're just too expensive for all of us to buy every different brand in search of the one that fills our individual needs. By the way, I do suspect that my ASI is indicating about 2-3 MPH faster than true, but like Jack says, if the comparisons are done on the same test bed then the results are still meaningful.

In my experience, the Kiev and the Whirlwind props are very similar with regard to smoothness. Both of mine have had minor vibrations - mostly when reducing the throttle and thereby unloading the prop somewhat. I have to say though that I can't blame it on the prop design because I have had neither of them tested for balance. I know that is something everyone should do but I don't have access to the proper equipment for balancing.

I also have to wonder if those vibrations may be caused by my exhaust system. It's an older version which is not as quiet as the newer ones we have now.